The present invention relates to an antiskid braking device for a motorcycle having an improved mounting structure.
Regarding an antiskid braking device which brakes over the shortest possible distance and stops a motorcycle without locking the wheels when braking suddenly or braking on a slippery road, a control device detects an indication that the wheels may lock and reduce the master cylinder pressure applied to the braking mechanism (brake caliper and the like) preventing the wheel from locking. When the indication that the wheel may lock diminishes, the control device actuates the pump unit to repressurize the control mechanism with an appropriate pressure. By repeating the aforementioned operation steps quickly, it is possible to brake and stop the motorcycle after it travels over the shortest possible distance.
Generally, in an antiskid braking device provided on a motorcycle, a single pump unit is employed to repressurize the braking mechanism on the front and rear wheels. Because the pump unit is relatively heavy, it is arranged almost in a central portion of the body frame so that the pump unit is located near the center of gravity of the body. Brake pipes extend to the back and the front of the body from the pump unit and, then, are connected to the control mechanisms and the master cylinders of the front and rear wheels.
The front wheel brake pipes which connect the braking mechanism and the master cylinder of a motorcycle to the pump unit extend a relatively long distance. Thus, generally, the middle portions of the brake pipes are formed of metallic pipes to avoid expansion of the pipes due to brake fluid pressure, and both ends of the metallic pipes are connected to the front wheel braking mechanism, the master cylinder and the pump unit through flexible brake hoses.
In one aspect, since the metallic pipe sections of the front wheel brake pipes extend a long distance from the front of the body to the rear as described above, there is a fear that the metallic pipes may hit the ground and be damaged when a motorcycle falls down.
Further, an electric wire harness which extends from the front to the rear of the body of the motorcycle is placed along the metallic pipes on the body frame of the motorcycle. Thus, the mounting space for the metallic pipes is reduced, but the electric wire harness is likely to interfere with the metallic pipes when assembled to the body frame, thereby hindering the assembly process.
Furthermore, in conventional motorcycles, since connecting sections which connect the front ends of the metallic pipes of the front wheel brake pipes to the brake hoses are arranged in a relatively forward position, the brake hoses are made short. Thus, there is a fear that the brake hose may be forcibly bent when steering, thereby leading to damage or leakage of brake fluid.
In another aspect, a prior art provides an antiskid braking device such as disclosed in Japanese Patent Application Laid-Open No. 2-11448, for example, in which the pump unit is mounted perpendicularly to the length of the body of a motorcycle and the brake pipe port section of the pump unit faces the side of the body. To facilitate connecting the brake pipes, the brake pipe port section protrudes from the side of the body frame.
In such prior art, since the pump unit is mounted perpendicularly to the longitudinal direction of the body and the brake pipe port section protrudes from the side of the body frame, when a motorcycle falls down or is hit on the side, there is a fear that the pump unit or the brake pipes may be damaged. In addition, since the brake pipes are grouped on the side of the pump unit, it is difficult to flexibly structure the brake pipes, thus providing a bad layout thereof.
Furthermore, since the pump unit is mounted perpendicularly to the longitudinal direction of the body, it is necessary to enlarge the width of the body frame to support the pump unit and place it above the drive chain to avoid interfering with the drive chain. Thus, the width and height of the driver's seat are necessarily increased so that foot contact to a pedal or ground becomes less accessible.
Still further, the heavy pump unit is offset from the center of the body along the width thereof, thus the bilateral weight balance of the motorcycle body can be adversely affected.
In such a motorcycle structure, the pump unit is fastened to the body frame via fixing brackets provided on the body frame. However, since the internal space of the motorcycle is limited, it is difficult to provide the body frame with a number of fixing brackets and, further, to fix the pump unit firmly. If fixing brackets are provided on a body frame, when the body frame is adapted to a motorcycle having no antiskid braking device easily, all the fixing brackets will be wasted.